In the standard picture of disc galaxy formation [1]}, [2]}, [3]}, galaxies consist of a dissipative
baryonic component and a non-dissipative dark matter component. Galaxies form hierarchially, and in this
process, baryons and dark matter acquire the same specific angular momentum (\(j\) ) via tidal-torques. This is
because tidal-torques are most effective in the linear and the trans-linear regimes, when baryons and dark matter are well-mixed. The
dark matter then collapses non-dissipatively, and the baryons dissipatively, likely with some cloud-cloud
collisions and possibly shocks (processes which are expected to rearrange \(j\)  but not remove it).
The baryons form rotating centrifugally-supported
discs at the centres of the potential wells. For a review of this scenario see [4]}.
This standard picture is able to correctly predict galaxy properties such as scale-lengths and sizes
if the baryons retain most of their initial \(j\) . It has been extended to
include additional physics effects and larger samples of galaxies by e.g., [5]}, [6]},
[7]}, [8]}, [9]}, [10]}, and [11]}.
